Note geth eth_call breaking change

CHANGELOG.md

@@ -154,6 +154,9 @@ Released with 1.0.0-beta.37 code base.
   - Removed old bower and meteor artifacts
   - Moved logo assets to own folder
   - Moved github assets to own folder
+- *Please note*: Geth [v1.9.12](https://github.com/ethereum/go-ethereum/releases/tag/v1.9.12) contains a breaking change for `eth_call` that will not default to your first account anymore if `from` is not set. If a sender is not explicitly defined, the `eth_call` will be executed from `address(0)`.
+  - This was done to avoid the same input behaving differently in different environments. You should never do `eth_call` without explicitly setting a sender.
+  - This means that Geth and Parity nodes may return different data for `eth_call` depending on your parameters.
 
 ### Fixed
 

docs/web3-eth.rst

@@ -1600,7 +1600,7 @@ Executes a message call transaction, which is directly executed in the VM of the
 Parameters
 ----------
 
-1. ``Object`` - A transaction object see :ref:`web3.eth.sendTransaction <eth-sendtransaction-return>`, with the difference that for calls the ``from`` property is optional as well.
+1. ``Object`` - A transaction object, see :ref:`web3.eth.sendTransaction <eth-sendtransaction-return>`. For calls the ``from`` property is optional however it is highly recommended to explicitly set it or it may default to `address(0)` depending on your node or provider.
 2. ``Number|String|BN|BigNumber`` - (optional) If you pass this parameter it will not use the default block set with :ref:`web3.eth.defaultBlock <eth-defaultblock>`. Pre-defined block numbers as ``"latest"``, ``"earliest"``, ``"pending"``, and ``"genesis"`` can also be used.
 3. ``Function`` - (optional) Optional callback, returns an error object as first parameter and the result as second.